Abby Kelley Foster (January 15, 1811 – January 14, 1887) was an American abolitionist and radical social reformer active from the 1830s to 1870s. She became a fundraiser, lecturer and committee organizer for the influential American Anti-Slavery Society, where she worked closely with William Lloyd Garrison and other radicals. She married fellow abolitionist and lecturer Stephen Symonds Foster, and they both worked for equal rights for women.
Her former home of Liberty Farm in Worcester, Massachusetts has been designated a National Historic Landmark.
Kelley's views became progressively more radical as she worked with abolitionists such as Angelina Grimke. She became an “ultra”, advocating not only the abolition of slavery, but also full civil equality for blacks. In addition, Garrison's influence led her to adopt the position of “non-resistance", which went beyond opposing war to opposing all forms of government coercion. Radical abolitionists led by Garrison refused to serve on juries, join the military, or vote. The Garrisonian call for the end of slavery and the extension of civil rights to women and African Americans caused controversy. Kelley's advocacy of the radical abolitionist movement prompted some opponents to call her a “Jezebel", as what she proposed threatened their sense of social structure. On the other hand, many fellow abolitionists praised her public speaking skills and her dedication to the cause. Kelley’s influence was shown by activist women being called “Abby Kelleyites". Radical abolitionism became known as “Abby Kelleyism.”